/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package cn.edu.thu.laud.utils.serde;

import java.nio.ByteBuffer;

import org.datanucleus.exceptions.NucleusDataStoreException;

/**
 * ByteAware wrapper that will create new instances of keys and return them
 * 
 * @author zhuoan
 * 
 */
public class ByteAwareConverter implements IConverter {

	private Class<?> targetClass;

	public ByteAwareConverter(Class<?> targetClass) {
		this.targetClass = targetClass;
	}

	@Override
	public Object getObject(ByteBuffer buffer, ConverterContext context) {

		ByteAware instance = createInstance();

		instance.parseBytes(buffer, context);

		return instance;

	}

	@Override
	public ByteBuffer writeBytes(Object value, ByteBuffer buffer, ConverterContext context) {

		return ((ByteAware) value).writeBytes(buffer, context);

	}

	@Override
	public String getComparatorType() {
		return createInstance().getComparatorType();
	}

	private ByteAware createInstance() {
		try {
			return (ByteAware) targetClass.newInstance();
		} catch (Exception e) {
			throw new NucleusDataStoreException(
					String.format(
							"Unable to create new instance of class %s.  Please make sure it has a no arg constructor",
							targetClass.getName()));
		}
	}

}
